Insights Into the Structural and Functional Evolution of Plant Genomes Afforded by the Nucleotide Sequences of Chromosomes 2 and 4 of Arabidopsis Thaliana

The rapidly accumulating genome sequence data from the plant Arabidopsis thaliana allows more detailed analysis of genome content and organisation than ever bafore possible in plants. The genome shows a surprisingly high level of genetic redundancy, with as many as 75% of gene products showing signficant homology to another protien of A. thaliana. Many duplicated genes occur in arrays of conserved order and indicate that A. thaliana is likely to have had a tetraploid ancestor. Analysis of the divergence of duplicated genome segments leads to the prediction of two major modes of plant genome evolution: macro-scale duplication and rearrangement of chromosomes and micro-scale translocation, duplication and loss of individual genes or small groups of genes.